Pages

Dec 21, 2011

The production flow in any factory has a very important associate that helps manufacturing achieve its optimum rate. That associate is one piece flow production.
When a production line design includes cellular work stations it is in the best interest of the management of the production operation to consider implementing one piece flow production. Including one piece flow production in the operation is the best way to have manufacturing create only products that are needed. As a product moves through the work stations of the production line there is no accumulation of partially completed products between the work cells.

The scenario called one piece flow production is very simplistic, but it yields excellent benefits. The queue that is allowed between work cells on the line in this scenario can only contain one product at any one time. The first work cell starts the production of a product and when the work is completed at that cell the product is placed in the queue for the second cell to begin its work. There is never more than one product in queue between work cells on the production line. If the queue immediately after a given cell has a product in it that is to be worked on by the following cell, the cell before that queue is idle and does not work. It is only when the queue after the cell is empty that the cell can work on a product.

This one piece flow production process may seem over-simplified, but actually it delivers great benefit to the overall operation. For example, if there is a problem with the work that is done at a given cell in the production line, and the line runs in such a way that each cell is allowed to produce as many products as it can. This could build up a large backlog of products that could be waiting in queue to be processed by the next work cell. Once the problem is discovered, it will be necessary to rework all those products in the queue that are defective, causing an increase in labor expense. If the problem is too great to be reworked, then the defective products may need to be scrapped, causing an increase in raw material losses. As the production line runs and products are accumulated between work cells there will need to be a place for all those partially completed products to be stored, increasing the need for warehouse space. These are definitely extra costs and losses that can be avoided by using one piece flow production.

In order to achieve an effective implementation of one piece flow production in a manufacturing operation, the output of each cell in the production line has to be able to routinely create good products. Each of the cells must be able to accomplish work that is consistently repeatable, so that the single product queue is always filled for the nest work cell. There can be no periodic downtime for equipment that is running on the production line. The proximity of tasks that are done in a well designed work cell can have a bearing on the time required to complete the work at any given cell. This is dictated by the way the production floor is laid out. The work area of any given cell must be designed so that the employees in that cell can reach resources and perform tasks in a reasonable time frame that allows for continuous work.

The design for one piece flow production is best accomplished with manufacturing automation. In fact the likelihood of creating a cost-effective production line with one piece flow production without manufacturing automation would be nearly impossible. The design of the work flow of the production line has to have very precise cycle times for each work cell in the line. Coordination of the movement of products from one cell to the next is easily dictated by well-defined manufacturing automation. The controller for each work cell must be set to give the cell or cells that it instructs timely orders, so that the work of each cell is in perfect relationship with the work of the other cells on the production line.

Cycle times are set up so that at the completion of the cycle at one work station the start of the cycle time at the next work station begins. It should be near a hand in glove relationship, as one work cell completes the next work cell begins its work. When a company is setting up manufacturing automation, one of the main goals of the completed automation process is to have one piece flow manufacturing in place because this type will yield optimum results.